Unless otherwise indicated herein, the materials described in this section are not prior art to the claims and are not admitted to be prior art by inclusion in this section.
A typical radio access wireless (RAN) network includes a number of base stations that radiate to define wireless coverage areas, such as cells and cell sectors, in which user equipment devices (UEs) such as cell phones, tablet computers, tracking devices, embedded wireless modules, and other wirelessly equipped communication devices, can operate. In turn, each base station may be coupled with network infrastructure that provides connectivity with one or more transport networks, such as the public switched telephone network (PSTN) and/or the Internet for instance. With this arrangement, a UE within coverage of the network may engage in air interface communication with a base station and may thereby communicate via the base station with various remote network entities or with other UEs served by the base station.
In general, a RAN may operate in accordance with a particular radio access technology or “air interface protocol,” with communications from the base stations to UEs defining a downlink or forward link and communications from the UEs to the base stations defining an uplink or reverse link. Examples of existing air interface protocols include, without limitation, Orthogonal Frequency Division Multiple Access (OFDMA (e.g., Long Term Evolution (LTE) or Wireless Interoperability for Microwave Access (WiMAX)), Code Division Multiple Access (CDMA) (e.g., 1×RTT and 1×EV-DO), and Global System for Mobile Communications (GSM), among others. Each protocol may define its own procedures for registration of UEs, initiation of communications, handover between coverage areas, and functions related to air interface communication.
In accordance with the air interface protocol, each coverage area may operate on one or more carrier frequencies or ranges of carrier frequencies In a frequency division duplex (FDD) arrangement, different carrier frequencies or ranges are used for the downlink than the uplink. Whereas, in a time division duplex (TDD) arrangement, the same carrier frequency or range is used for the downlink and uplink and is allocated over time among downlink and uplink communications.
Further, each coverage area may define a number of subsidiary air interface channels for carrying information between the base station and the UEs. These channels may be defined in various ways, such as through frequency division multiplexing, time division multiplexing, and/or code-division multiplexing, for instance. By way of example, each coverage area may define one or more downlink control channels and one or more downlink shared channels having resources that the base station may allocate on an as-needed basis to carry downlink communications to UEs, and each coverage area may provide a downlink reference signal that UEs can detect and measure as a basis to determine downlink channel quality. Further, each coverage area may define one or more uplink control channels and one or more uplink shared channels having resources that the base station may allocate on an as-needed basis to carry uplink communications from UEs, and each UE may provide an uplink reference signal that the base station may measure as a basis to determine a UE's uplink channel quality.
When a UE enters into a base station's coverage area, the UE may register or attach with the base station and may then operate in a connected mode or an idle mode. In the connected mode, the UE may have an assigned radio link layer connection with the base station (which, depending on the air interface protocol, could be one or more dedicated air interface traffic channels or could be a seat allowing the UE to engage in bearer communications on one or more shared traffic channels). In that mode, the UE may thus engage in active bearer communication such as packet-data communication and/or voice calls, transmitting bearer data on uplink traffic channel resources to the base station and receiving bearer data on downlink traffic channel resources from the base station.
After a timeout period of no bearer data communication between the base station and the UE, or for other reasons, the UE may then transition from the connected mode to the idle mode, with the base station releasing the UE's radio link layer connection, so as to conserve resources. In the idle mode, the UE may then simply monitor a downlink control channel to receive overhead information and to check for any page messages for the UE. Further, the UE may then engage in signaling with the base station to transition back to the connected mode if and when the UE receives a page message from the base station indicating an inbound bearer communication or if and when the UE seeks to engage in outbound bearer communication.